Many aircraft designs incorporate multiple engines for power generation. Multi-engine aircraft are generally designed to fly even when one of the aircraft's engines is completely inoperable. Operating such an aircraft, however, can present a serious challenge to a pilot, particularly during the critical transition period between normal flight and flight with one or more inoperable engines. This is especially true where an engine fails catastrophically and without warning. As such, pilots of such aircraft need to be well trained and sufficiently experienced to skillfully manage the situation where one or more engines fail.
In addition, it is desirable to train pilots in an environment and under conditions reflecting an actual in flight engine failure as closely as possible. At the same time, it is desirable to train the pilots without undue risk to the pilot or other personnel and without causing permanent damage to the aircraft, its engines, or its power transmission components.
Normally, the engines of a multi-engine aircraft are of approximately the same size and have approximately the same peak power output. Moreover, the engines are typically operated together at approximately the same speed and power output during flight. During emergencies, these engines are generally designed to produce power well in excess of the normal operating power so that the aircraft can still fly. Although the normal operating range of the engines is generally well below the level at which permanent engine or transmission damage will occur, some degree of permanent engine and/or transmission damage may occur when an engine is operated at or near peak power output for any length of time.
In addition, the life of an aircraft engine is significantly reduced by operating above a certain power output level because of the increased wear and stress on the engine and transmission. This increased strain on the remaining engine or engines is an undesirable condition which both reduces engine reliability and increases the risk to pilots. This increased strain should therefore be avoided if at all possible, and particularly during pilot training.
Compounding the above problems, modern aircraft engines and engine controllers are designed to automatically respond to abrupt changes in engine loading by accelerating the engine at a high rate. This automatic response, although highly desirable in the event of an actual engine failure, in many cases precludes the use of traditional training methods, such as “throttle chops.” A throttle chop is an abrupt manual throttle reduction by a trainer riding in the aircraft with the trainee pilot to simulate loss of engine power. If a throttle chop is attempted at medium to high power in a modern aircraft, the good engine or engines may in some cases accelerate so quickly that either a transmission or a good engine is likely to experience a damaging over-torque or over-temperature condition before the pilot can reduce power.
For the reasons outlined above, there remains a need for an improved method of pilot training. In particular, there is a need for pilot training methods that are highly realistic, maintain the safety of the pilot and protect against permanent damage to the aircraft.